C# Is this a correct use of Delegate and Callback method using delegate

Question

This code perfoms well.

I'm busy learning delegates in C# and merely want to know whether this is the correct use of Delegate and Callback method using delegate.

using System;

namespace DelegatesCallbackRealDemoApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Del handler = DelegateMethod;
            DataProgression(1, handler);

            Console.Read();
        }

        static void DelegateMethod(string message)
        {
            Console.WriteLine("Progression : " + message + " %");
            DelegateMethodPause(1);
        }


        static void DelegateMethodPause(int sec)
        {
            System.Threading.Thread.Sleep(sec*1000);
        }

        static void DataProgression(int param1, Del callback)
        {
            for (int i = 0; i < 100; i++)
            {
                callback(param1.ToString());
                param1++;
            }
        }
    }
}

Answer 1

Yes that is the correct approach on how delegates would work. A delegate is simply a function object and allows you to pass functions around as data.

As an aside you should rarely need to declare the delegate type(s) yourself and instead rely on the pre-defined ones. This reduces your code and speeds things up. .NET already provides delegates for any method that accepts up to 16 parameters (at last check) and optionally return a value.

Action<...> - void returning functions
Func<...,T> - T returning functions

   static void DataProgression(int param1, Action<string> callback)  
    {  
        for (int i = 0; i < 100; i++)  
        {  
             callback(param1.ToString());  
             param1++;  
        }  
    }  
     
   //Long form  
   Action<string> foo = DelegateMethod;  
   DataProgression(1, foo);  
     
   //Short form  
   DataProgression(1, DelegateMethod);  
     
   //Short, short form  
   DataProgression(1, x => Console.WriteLine(x));